With the advent of the network era, various content distribution technologies keep emerging, and information sharing can be easily achieved with the aid of existing networks and technologies. A variety of industries involving networks are developing prosperously and operators providing services to users by means of networks appear accordingly. The operators provide various services to the users through the networks, and the users can use the services provided by the operators after paying a certain fee to the operators. The content provided by content providers is the core of the services provided by the operators, and the users purchase the content from the operators and use the content through a user terminal.
In order to protect interests of the operators and the content providers, a content protection system appears accordingly, where content protection is achieved by the a content protection system through content encryption and access control, so the interests of the operators and the content providers are protected to a certain degree and unauthorized spread of the contents is constrained.
For example, after a user pays a certain fee to an operator to purchase content from the operator, the operator distributes unencrypted content to an authorized user terminal through a network. After obtaining the content, the authorized user terminal may use the content or forward the content at will, for example, to other authorized terminals or unauthorized terminals. As the content is unencrypted, each terminal can process the content, and such a situation where the content is uncontrollable is a fatal blow to the operators and content providers.
Due to the disadvantages of the above technical solutions, the operators introduce a content protection system in their operation schemes. After a user pays a certain fee to an operator to purchase content from the operator, the operator encrypts the content by using the content protection system, and distributes the encrypted content and authorization to authorized user terminal through a network. When obtaining the encrypted content only, the authorized user terminal still cannot process the contents normally, and the user terminal can only normally process the encrypted content when acquiring the authorization of the operator at the same time. The so-called authorization is that the operator grants a right of using a subscribed service to a user, and the authorization has various forms, for example, the authorization may include a content decryption key, or a deadline of using the content by the user. As for the authorization, different content protection vendors have different definitions, but one thing in common is that the user can only normally use the subscribed contents after obtaining the authorization of the operator.
The authorization may be locally stored in the terminal, and each vendor performs security processing on the local authorization to prevent the authorization from unauthorized replication. Some vendors think that authorization locally stored in the terminal is less secure than authorization stored in a server at an operator side, so the vendors store the authorization in the server at the operator side. The user terminal needs to apply for the authorization from the server before decrypting the content, and a server end delivers the authorization to the user terminal after verifying validity of the user terminal. In a word, the authorization cannot be forwarded at will, and an unauthorized terminal or an authorized terminal that does not subscribe to the corresponding service cannot acquire the authorization.
According to the existing technical solutions above, though the content is prevented from unauthorized spread, the content protection also brings inconveniences to the terminal users. In a current operation scheme, it is assumed that a user has (1+n) terminals, and when the user uses an account number 1 to subscribe to encrypted content for a terminal 1, the user can only use the content on the terminal 1. If the user uses a terminal (1+n) to process the encrypted content, a new account number (1+n) has to be created and a complete account opening and subscription operation is repeated to use the same content on the terminal (1+n). That is, different terminals of the same user cannot conveniently share authorization of the content subscribed by the user, so that the user cannot conveniently use the subscribed content on multiple terminals. Therefore, this operation scheme causes enormous inconveniences to the use of the service by the user, influences user experience, reduces a satisfaction degree of the customer, and harms the interests of the operators and content providers.